Fair Value Measurement of Assets and Liabilities - Recurring and Non-Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Investment securities
Equity securities	$ 54,379	$ 41,410
Available for sale
Available for sale debt securities	1,689,388	1,566,801
Non-recurring fair value measurements:
Loan servicing rights	14,400
Unpaid principal balances of loans held for sale	115,000	74,500
U.S. Treasury securities
Available for sale
Available for sale debt securities	52,621	50,943
U.S. government agency securities
Available for sale
Available for sale debt securities	27,924	29,243
Obligations of states and political subdivisions
Available for sale
Available for sale debt securities	147,505	170,051
Residential mortgage-backed securities
Available for sale
Available for sale debt securities	1,382,726	1,254,786
Corporate and other debt securities
Available for sale
Available for sale debt securities	78,612	61,778
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements
Investment securities
Equity securities	46,897	41,410
Available for sale
Available for sale debt securities	52,621	50,943
Loans held for sale	0	0
Other assets	0	0
Total assets	99,518	92,353
Liabilities
Other liabilities	0	0
Total liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements \| U.S. Treasury securities
Available for sale
Available for sale debt securities	52,621	50,943
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements \| U.S. government agency securities
Available for sale
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements \| Obligations of states and political subdivisions
Available for sale
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements \| Residential mortgage-backed securities
Available for sale
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Recurring fair value measurements \| Corporate and other debt securities
Available for sale
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Non-recurring fair value measurements
Non-recurring fair value measurements:
Collateral dependent loans	0	0
Loan servicing rights	0	0
Foreclosed assets	0	0
Total	0	0
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements
Investment securities
Equity securities	0	0
Available for sale
Available for sale debt securities	1,635,402	1,515,178
Loans held for sale	120,599	76,113
Other assets	468,275	158,532
Total assets	2,224,276	1,749,823
Liabilities
Other liabilities	170,273	43,926
Total liabilities	170,273	43,926
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements \| U.S. Treasury securities
Available for sale
Available for sale debt securities	0	0
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements \| U.S. government agency securities
Available for sale
Available for sale debt securities	27,924	29,243
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements \| Obligations of states and political subdivisions
Available for sale
Available for sale debt securities	146,140	169,371
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements \| Residential mortgage-backed securities
Available for sale
Available for sale debt securities	1,382,726	1,254,786
Significant Other Observable Inputs (Level 2) \| Recurring fair value measurements \| Corporate and other debt securities
Available for sale
Available for sale debt securities	78,612	61,778
Significant Other Observable Inputs (Level 2) \| Non-recurring fair value measurements
Non-recurring fair value measurements:
Collateral dependent loans	0	0
Loan servicing rights	0	0
Foreclosed assets	0	0
Total	0	0
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements
Investment securities
Equity securities	0	0
Available for sale
Available for sale debt securities	1,365	680
Loans held for sale	0	0
Other assets	0	0
Total assets	1,365	680
Liabilities
Other liabilities	0	0
Total liabilities	0	0
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements \| U.S. Treasury securities
Available for sale
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements \| U.S. government agency securities
Available for sale
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements \| Obligations of states and political subdivisions
Available for sale
Available for sale debt securities	1,365	680
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements \| Residential mortgage-backed securities
Available for sale
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) \| Recurring fair value measurements \| Corporate and other debt securities
Available for sale
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) \| Non-recurring fair value measurements
Non-recurring fair value measurements:
Collateral dependent loans	42,807	39,075
Loan servicing rights	14,373	1,591
Foreclosed assets	6,679	10,807
Total	63,859	51,473
Fair Value \| Recurring fair value measurements
Investment securities
Equity securities	54,379	41,410
Available for sale
Available for sale debt securities	1,689,388	1,566,801
Loans held for sale	120,599	76,113
Other assets	468,275	158,532
Total assets	2,332,641	1,842,856
Liabilities
Other liabilities	170,273	43,926
Total liabilities	170,273	43,926
Fair Value \| Recurring fair value measurements \| U.S. Treasury securities
Available for sale
Available for sale debt securities	52,621	50,943
Fair Value \| Recurring fair value measurements \| U.S. government agency securities
Available for sale
Available for sale debt securities	27,924	29,243
Fair Value \| Recurring fair value measurements \| Obligations of states and political subdivisions
Available for sale
Available for sale debt securities	147,505	170,051
Fair Value \| Recurring fair value measurements \| Residential mortgage-backed securities
Available for sale
Available for sale debt securities	1,382,726	1,254,786
Fair Value \| Recurring fair value measurements \| Corporate and other debt securities
Available for sale
Available for sale debt securities	78,612	61,778
Fair Value \| Non-recurring fair value measurements
Non-recurring fair value measurements:
Collateral dependent loans	42,807	39,075
Loan servicing rights	14,373	1,591
Foreclosed assets	6,679	10,807
Total	63,859	$ 51,473
Fair Value \| NAV \| Recurring fair value measurements
Investment securities
Equity securities	$ 7,500

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Carrying amount as of the balance sheet date of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Fair value of the collateral dependent impaired loans.

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